Conventional vehicle restraint or seat belt systems combining a lap belt and an upper torso or shoulder belt to restrain an occupant or passenger in a vehicle are well known. These three-point restraint systems integral to the vehicle are usually used with seats offering rigid support for the belts. As typically used in a vehicle, the three-point restraint system consists of a single belt having its opposite ends mounted to a pair of retractors with a seat belt tongue connected to the belt intermediate to the belt ends. The tongue may be swung across the person and engaged with a buckle affixed to the seat thereby positioning one portion of the belt across the lap and another portion of the belt across the upper torso. In some systems, only one end of the belt is mounted to a retractor while the other end is anchored to the seat or vehicle. These seat belt systems are active restraint devices, generally requiring a passenger to positively engage the restraints about the person for them to be effective.
Vehicles, such as buses, which require the passive protection provided by deforming or deflecting seats, present certain challenges regarding the integration of active restraint seat belt systems. In a school bus seat combining active and passive restraint systems, both of the restraint systems may need to be able to perform their functions and the seat may still need to conform to the regulations set forth in FMVSS 222, which is incorporated herein by reference. In addition to two-point active lap restraint systems, examples of vehicle seats designed to combine both active and passive restraint systems in conformity with FMVSS 222 are found in commonly owned U.S. Pat. No. 6,485,098, and U.S. Pat. No. 6,886,889, the disclosures of which are now incorporated herein by reference.
Two or three-point restraint systems may cooperate with various add-on restraint systems, for example, torso harnesses, positioning harnesses, portable child seats and booster seats, for use on buses and other vehicles. For example, portable seats for children up to about 100 pounds may be mounted to a vehicle for restraint of a passenger or occupant. Commonly owned U.S. patent application Ser. No. 10/245,983 discloses supplemental restraint systems for use with a school bus seat in accordance with FMVSS 222. Examples of booster seats are disclosed in U.S. Pat. No. 5,797,654 to Stroud, U.S. Pat. No. 5,829,834 to Silverman, and U.S. Pat. No. 5,685,604 to Kain, which are incorporated by reference herein.
These add-on child restraint systems may be coupled to a vehicle seat using various connectors and anchorage systems. The federal government has mandated that child restraint anchorage systems be installed in most vehicles, including cars, trucks, vans, sports utility vehicles (SUVs) and certain school buses. These regulations, codified at 49 C.F.R. § 571.225 (FMVSS 225), incorporated herein by reference, require two lower anchorages and an upper tether anchorage of specified configuration, location and strength parameters. Similarly, 49 C.F.R. § 571.213 (FMVSS 213), incorporated herein by reference, specifies the dimensions of tether hooks used to attach a tether strap to a tether anchorage.